2020 POTD Thread Archive

silverhawk said:
Did they take anything or destroy machines? I don't like small cats that damage stuff.
Click to expand...

Hahaha, only my ego, first time i walk in i slipped on the oil and landed on my back, at first did not know what had done it, but later found the oil footprints on everything.
 
BGHansen said:
POTD was repairing my Post drafting machine. Yeah, I can read a calendar and know it’s year 2020. . . In my defense, I hadn’t used it for about 30 years, but frankly find “old tech” still has its place on occasion.

For those under 50 who have never seen one of these, mine is a Post/Mutoh drafting machine. The base is fixed to the drawing table. There are two swing arms with a pulley in between the two, plus pulleys on either end of the swing arms. The drafting detail (sorry, the proper name escapes me) has an infinitely adjustable base (in rotation) that can be locked into an angular position. Once locked in place, you can move the drafting head around the table and the X/Y scales stay parallel to your work. There’s a push button on the head that lets the scale rotate and lock into other angles in 15 deg. increments.

So, draw a base line on the X-axis and need to draw a 45 angle, push the button and swing the head to a 45, release the button and the head locks at that angle. There’s a protractor on the base with minutes graduations so you can read or draw angles in between.

When I work from an existing drawing, I tape it to the table and rotate the head until the bottom or side scale line up with the appropriate line, then lock the angle of the head. I have scales in fractional inches, millimeters and decimal inches.

I was going to use the drafting machine to dimension a computer scan of a part and discovered one of the pulley bands was snapped. The two arms have tensioning rods so the bands can be tightened on the pulleys. If they slip, you lose angular position. My guess is the bands are stainless and looked to be silver soldered together.


Busted band doesn't run too well on the pulley. . .
View attachment 326535
Looking at the other band, looked to be silver soldered together
View attachment 326536


My fix was to spot weld the band. My spot welder is plugged into a foot pedal so weld time is controlled by the tap time of my foot. I can’t adjust current, only weld time. Well, a tap of the foot for under a half-second blew through the band. I was able to get some really quick taps of the foot to weld around the big hole I made, so it’s holding for now. Cleaned up the inside surface with a Scotchbrite wheel.


Yeah, not my best spot weld. Hit a few more around the hole and it's holding fine
View attachment 326537


The tensioning is done with a steel rod with a bolt on one end. The bolt head has a keyway cut, to tighten the band you stick a nail or small Allen wrench through a hole in the base casting into the keyway, then turn the rod to unscrew the bolt.


The steel rod and bolt are used to tension the pulley band
View attachment 326538

Slip the band over the pulleys and turn the white knob to unscrew the bolt to tighten the band
View attachment 326539

Use an Allen wrench in the base to catch the key way in the bolt so it didn't turn with the rod
View attachment 326540


Works great again and works really well for me getting quick dimensions off an existing part. Pictures here are of a 4x scale Erector set part. I flattened an original part and scanned it on our computer, then scaled up in Photoshop for the hardcopy. I’ve got another thread showing the Erector set part I was making.


Yes, I know it's ancient technology, but I got the dimensions for this drawing in about 15 minutes. I'm accurate to about 0.010" which was "close enough" for my project. Still need to learn Fusion 360 or Solidworks one of these days. . .
View attachment 326541
View attachment 326542


Thanks for looking,

Bruce
Click to expand...

BGHansen said:
POTD was repairing my Post drafting machine. Yeah, I can read a calendar and know it’s year 2020. . . In my defense, I hadn’t used it for about 30 years, but frankly find “old tech” still has its place on occasion.

For those under 50 who have never seen one of these, mine is a Post/Mutoh drafting machine. The base is fixed to the drawing table. There are two swing arms with a pulley in between the two, plus pulleys on either end of the swing arms. The drafting detail (sorry, the proper name escapes me) has an infinitely adjustable base (in rotation) that can be locked into an angular position. Once locked in place, you can move the drafting head around the table and the X/Y scales stay parallel to your work. There’s a push button on the head that lets the scale rotate and lock into other angles in 15 deg. increments.

So, draw a base line on the X-axis and need to draw a 45 angle, push the button and swing the head to a 45, release the button and the head locks at that angle. There’s a protractor on the base with minutes graduations so you can read or draw angles in between.

When I work from an existing drawing, I tape it to the table and rotate the head until the bottom or side scale line up with the appropriate line, then lock the angle of the head. I have scales in fractional inches, millimeters and decimal inches.

I was going to use the drafting machine to dimension a computer scan of a part and discovered one of the pulley bands was snapped. The two arms have tensioning rods so the bands can be tightened on the pulleys. If they slip, you lose angular position. My guess is the bands are stainless and looked to be silver soldered together.


Busted band doesn't run too well on the pulley. . .
View attachment 326535
Looking at the other band, looked to be silver soldered together
View attachment 326536


My fix was to spot weld the band. My spot welder is plugged into a foot pedal so weld time is controlled by the tap time of my foot. I can’t adjust current, only weld time. Well, a tap of the foot for under a half-second blew through the band. I was able to get some really quick taps of the foot to weld around the big hole I made, so it’s holding for now. Cleaned up the inside surface with a Scotchbrite wheel.


Yeah, not my best spot weld. Hit a few more around the hole and it's holding fine
View attachment 326537


The tensioning is done with a steel rod with a bolt on one end. The bolt head has a keyway cut, to tighten the band you stick a nail or small Allen wrench through a hole in the base casting into the keyway, then turn the rod to unscrew the bolt.


The steel rod and bolt are used to tension the pulley band
View attachment 326538

Slip the band over the pulleys and turn the white knob to unscrew the bolt to tighten the band
View attachment 326539

Use an Allen wrench in the base to catch the key way in the bolt so it didn't turn with the rod
View attachment 326540


Works great again and works really well for me getting quick dimensions off an existing part. Pictures here are of a 4x scale Erector set part. I flattened an original part and scanned it on our computer, then scaled up in Photoshop for the hardcopy. I’ve got another thread showing the Erector set part I was making.


Yes, I know it's ancient technology, but I got the dimensions for this drawing in about 15 minutes. I'm accurate to about 0.010" which was "close enough" for my project. Still need to learn Fusion 360 or Solidworks one of these days. . .
View attachment 326541
View attachment 326542


Thanks for looking,

Bruce
Click to expand...



I’m well under 50 but happen to know what a drafting table is.

My parents were mechanical engineers (retired now) and I remember them working on such tables many many years ago.

IIRC they should still have one in storage in the basement. Next time I visit I will look for it and take some pictures.


Sent from my iPhone using Tapatalk
 
A little shop time this morning and I finally got the Tee nut finished for the compound on my 9A.
Nothing as intricate or spectacular as some of the things you fellas turn out but I'm happy with it.
Went the Sharpie route to color it.

DSCN7930.JPG
 
Ah Yes, the Sharpie, the shop wonder tool, has multiple uses

1 - marker to lay out bolt holes and cut lines
2 - poorman’s Dykem in a pen applicator
3 - poorman’s bluing applicator

truly a wonder accessory in the shop.............:)
 
I feel better now about my initial snarky response (did he blue it with a sharpie?). Truth is, I do all kinds of touch-up with a sharpie. Have you tried the industrial sharpies yet? There more like melanite vs. salt blue. It's like a whole 'nuther level...
 
Oh great. Something else I just HAVE to order now. Thanks Pontiac.

pontiac428 said:
I feel better now about my initial snarky response (did he blue it with a sharpie?). Truth is, I do all kinds of touch-up with a sharpie. Have you tried the industrial sharpies yet? There more like melanite vs. salt blue. It's like a whole 'nuther level...
Click to expand...
 
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